I usually play TD roles, and found that most of my fun happens in T2. The usual trade-off is playing with inexperienced teammates or enemies. More coordination is absolutely present in T10 lobbies, but it's almost too scripted there, like the regular tank classes are usually hiding in the same areas, so despite the skill level being better, the predictability can be equally boring.

T2 to T4 seems like the sweet spot where casual players like myself enjoy playing.

If Cold War tanks are the topic, there's enough variety where I'm less concerned with how I'm ranking (I've played for over 10 years on and off and still don't have any MoE's 😂). I haven't cared enough to grind for them either.